<!DOCTYPE html>
<html lang="en">
<head>
  <meta charset="UTF-8">
  <meta http-equiv="X-UA-Compatible" content="IE=edge">
  <meta name="viewport" content="width=device-width, initial-scale=1.0">
  <title>Document</title>
</head>
<body>
  <div id="app">
    <!-- <input type="text" v-model="uname" /> -->

    <!-- <input type="text" v-bind:value="uname" v-on:input="changeUname"/> -->
    
    <input type="text" :value="uname" @input="changeUname"/>
  </div>

  <script src="./vue.js"></script>
  <script>
    const vm = new Vue({
      el: '#app',
      data: {
        uname: 'qwer'
      },
      methods: {
        changeUname(e) {
          this.uname = e.target.value
        }
      }
    })
  </script>
</body>
</html>